Wear warning and replacement standards for guide components of motorcycle wheel hub casting molds | Maintenance of guide column guide sleeve for aluminum casting molds
The excessive clearance between the guide column and guide sleeve of the motorcycle wheel hub casting mold is the source of the problem of aluminum running on the 40% parting surface and mold alignment deviation.
The single-sided gap between the guide column and guide sleeve is greater than 0.035mm, the positioning of the mold is offset, the parting surface is misaligned, the local gap becomes larger, and the probability of aluminum running increases by 54%.
The nitride layer on the surface of the guide column wears down to below 0.008mm, and the steel substrate rubs directly, increasing the wear rate by 2.9 times and rapidly expanding the gap.
The lubrication cycle of the guide pair exceeds 45 cycles, resulting in high temperature caused by dry friction, surface bite and strain, and a depth of strain on the guide column surface exceeding 0.02mm that cannot be repaired.
The coaxiality deviation of the guide column is greater than 0.02mm, and the clamping process is continuously biased. The wear of one side of the guide surface is much faster than the other side, and the gap is uneven.
The interference fit of the guide sleeve during press fitting is less than 0.01mm, causing displacement of the guide sleeve under production vibration, continuous deviation of the guide reference, and repeated misalignment of the sealing surface.
The motorcycle wheel hub casting mold is mostly single cavity, with high opening and closing frequency, and the guide system loss rate is higher than that of multi cavity structural casting molds. Low pressure die-casting molds (LPDC), reverse pressure casting molds (CPC), gravity casting molds, differential pressure casting molds for wheel hubs, low-pressure casting molds for wheel hubs, aluminum alloy wheel hub molds, aluminum casting forming molds, low-pressure casting tooling molds, and guide parts belong to high-frequency loss spare parts. Zhejiang Xinfeng Machinery tracks the maintenance records of overseas customers' molds. Many foundries lack the habit of guiding gap detection, and only stop for maintenance after a large amount of aluminum running and burrs break out. Cleaning burrs takes up a lot of working hours. Many factories in Southeast Asia operate in two consecutive shifts, lacking dedicated mold maintenance personnel, and the problem of guide wear has been neglected for a long time. The material selection for the guide column is significantly different between Cr12MoV and H13. Cr12MoV has better wear resistance for the guide components, with a 67% increase in service life under the same working conditions and a procurement cost increase of about 31%. The surface of the guide post is polished with Ra0.4 and treated with nitriding to reduce the risk of bite strain; The polishing pattern follows the axial direction, resulting in lower friction resistance. Excessive clamping speed will intensify the guiding impact. It is recommended to control the low-speed clamping speed within 80mm/s to reduce the impact load. The layout of the internal oil groove of the guide sleeve is unreasonable, and there is insufficient retention of lubricating grease. The lubrication of the guide pair is ineffective, and the oil groove volume should accommodate at least 0.12ml of lubricating grease. Many low-priced molds are matched with ordinary carbon steel guide parts, which are not nitrided and can strain after hundreds of molds are put into production, making them unsuitable for long-term mass production conditions for export.
FAQ
1. Question: What is the warning threshold for the unilateral gap between the guide column and guide sleeve?
Answer: If the unilateral gap exceeds 0.035mm, the risk of positioning deviation increases.
2. Question: What is the warning value for the remaining thickness of the nitride layer on the guide pillar?
Answer: The wear of the nitride layer is less than 0.008mm, and the wear rate accelerates rapidly.
3. Question: What is the maximum interval between lubrication of guide components?
Answer: The lubrication interval of the guiding pair should not exceed 45 cycles.
4. Question: What is the upper limit of coaxiality qualification for guide columns?
Answer: The coaxiality deviation should not exceed 0.02mm.
5. Question: How much longer does the lifespan of Cr12MoV guide columns increase compared to H13?
Answer: The wear resistance life is increased by 67% under the same working conditions, and the purchase price is higher.
6. Question: What is the recommended speed upper limit for the low-speed segment of mold closing?
Answer: The low-speed section of the mold should be controlled within 80mm/s to reduce impact.
